From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3D61F3876A4; Sat, 26 Sep 2026 11:48:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790423302; cv=none; b=DXjnQfqEGP9+GrvTyxwBgUD5ZBem9GleakXMzEcxSS3cO9/Tsf7m/2wDPzIIixy1wxtimu5dXn6gTrEaGhehYBveZzuquuLQMlj4C/7TEKLUgCMbhLVTBAUfw9QatdDmR7r4c0KGSwzIOyNA6UtXX2+9pOjHYdueICKYiJGFZIw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790423302; c=relaxed/simple; bh=6IPezDTQuoTfLo1a0Abvz5qH2+BAQ0rwPPdwFnlgIUc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=X3fot75q/SdGXAyLtedJG6vkJkPROulOczCvZ134qoIAgJ1Im0IjMh4YSwEJMADMzXdLa1zOqTixWtTS4FmfHpqmwz8uCF49NVX2yDisDpobghiS6Qwfd2zTBcKV+bHqIhZ8mxNmU6LKjOTN/e6CJ9kP36ScvBBPNKnJWvlHLNo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TN60UBBi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TN60UBBi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D13421F000FF; Sat, 26 Sep 2026 11:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790423300; bh=CPA8JMT9eU1pOHwrKFv2RoLmUTRfETmtbV4Zk3VVkd8=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=TN60UBBi+PkQD6jZzk0VpRUmOtOKWV8VcqhSNrzr3ANkMeawJQrIcndKdpRSP15PW U3BmdOUgTqOpZPPvhtXGHtbhUZYOnfyu4szOL9vRfp01TYVQGNRTTKK/XIAuF4ujw6 Oj8JMiOi4YSZT940AZnfDIGqArAFCUQK2qQs+HjCqpTDiv8VsDIqC4soqvE5ZlGRVt syUrzBz08iwaQ2RC3KWzG4D2PU6vVNpYGMAGMoANpv59CJvFyh6Rz+KJvoYNAofrvj WTLejdRlXGbyS3TjMzmAgBFkWjPBfyZ7JJm3oP3Fvzgj4nsYJHsAwCg/bS0NjU04Vn 3QvC+3yd+MeQw== Message-ID: <230f4080d975d1960a5f38e53d9d43242acaeeed.camel@kernel.org> Subject: Re: [PATCH v2 04/14] ceph: simplify atomic_open to use finish_no_open() From: Jeff Layton To: NeilBrown Cc: Alexander Viro , Christian Brauner , Chuck Lever , Jori Koolstra , Mateusz Guzik , Dorjoy Chowdhury , Trond Myklebust , Anna Schumaker , Andreas Gruenbacher , gfs2@lists.linux.dev, Ilya Dryomov , Alex Markuze , Viacheslav Dubeyko , ceph-devel@vger.kernel.org, Paulo Alcantara , Namjae Jeon , linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Date: Sat, 26 Sep 2026 07:48:17 -0400 In-Reply-To: <179037298028.37859.3168205779174130691@noble.neil.brown.name> References: <20260919022441.3305170-1-neilb@ownmail.net> <20260919022441.3305170-5-neilb@ownmail.net> <179037298028.37859.3168205779174130691@noble.neil.brown.name> 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text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-2.fc44) Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Sat, 2026-09-26 at 07:49 +1000, NeilBrown wrote: > On Thu, 24 Sep 2026, Jeff Layton wrote: > > Another LLM review: > >=20 > > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > > > index bd3e3f5c269e..83ceb2906f85 100644 > > > --- a/fs/ceph/file.c > > > +++ b/fs/ceph/file.c > >=20 > > [ ... ] > >=20 > > > @@ -977,33 +976,25 @@ int ceph_atomic_open(struct inode *dir, struct = dentry *dentry, > > > } > > > if (err) > > > goto out_req; > > > - if (dn || d_really_is_negative(dentry) || d_is_symlink(dentry)) { > > > - /* make vfs retry on splice, ENOENT, or symlink */ > > > - doutc(cl, "finish_no_open on dn %p\n", dn); > > > - err =3D finish_no_open(file, dn); > > > - } else { > > > - if (IS_ENCRYPTED(dir) && > > > - !fscrypt_has_permitted_context(dir, d_inode(dentry))) { > > > - pr_warn_client(cl, > > > - "Inconsistent encryption context (parent %llx:%llx child %llx:%= llx)\n", > > > - ceph_vinop(dir), ceph_vinop(d_inode(dentry))); > > > - goto out_req; > > > - } > > > + if (IS_ENCRYPTED(dir) && > > > + !fscrypt_has_permitted_context(dir, d_inode(dentry))) { > > > + pr_warn_client(cl, > > > + "Inconsistent encryption context (parent %llx:%llx child %= llx:%llx)\n", > > > + ceph_vinop(dir), ceph_vinop(d_inode(dentry))); > > > + goto out_req; > > > + } > >=20 > > The fscrypt check used to run only when the dentry was positive, not > > a symlink, and had no alias. Now it runs unconditionally, but > > d_inode() can still be NULL here: a lookup that found nothing leaves > > a negative dentry with err =3D=3D 0, and when the MDS reply splices an > > alias the original dentry is never instantiated. > >=20 > > fscrypt_has_permitted_context() dereferences its child argument > > without checking for NULL: > >=20 > > fs/crypto/policy.c:fscrypt_has_permitted_context() { > > ... > > if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) && > > !S_ISLNK(child->i_mode)) > > return 1; > > ... > > } > >=20 > > Every other in-tree caller passes a known inode, while this one can > > pass NULL. An open of a name that does not exist in an encrypted > > directory reaches this through lookup_open() -> atomic_open() -> > > ceph_atomic_open(). > >=20 > > Could the fscrypt check stay behind the positive-dentry test, as > > before? >=20 > Alternately: can we simply remove the fscrypt check? I don't know a > whole lot about fscrypt, but it seems that ceph_open() does all > necessary fscrypt checks, and we already didn't need this one before > calling ceph_open(). >=20 > You added this in > Commit: 94af0470924c ("ceph: add some fscrypt guardrails") > but the commit doesn't explain why ceph_atomic_open() needed more that > ceph_open() needed. >=20 Yes, let's just drop it. I had an LLM verify that too, and here's it's rationales: Three reasons to remove rather than re-nest it: 1) For regular files it's redundant. finish_open() calls ceph_open(), which calls fscrypt_file_open(). That does the same fscrypt_has_permitted_context() against the parent (d_parent's inode is dir on this path), plus fscrypt_require_key(), which the open-coded version doesn't. 2) It's broken as written. err is 0 at that point, so tripping it returns 0 from ->atomic_open with FMODE_OPENED clear and f_path.dentry still DENTRY_NOT_SET. That hits the WARN_ON() in atomic_open() in fs/namei.c and gives back -EIO instead of -EPERM. Clearly it has never fired in testing. 3) The only thing it covers that ceph_open() doesn't is a directory child (symlinks and spliced/negative dentries all go to finish_no_open). But that coverup() has no context check at all, unlike ext4/f2fs/ubifs which check S_ISDIR||S_ISLNK children in -> via the normal lookup path -- including everything finish_no_open() bounces back to the VFS -- are already unchecked. --=20 Jeff Layton